1. Field of the Invention
This invention relates to an optical element and an optical apparatus using the same, and is particularly suitable for the various optical systems of a photographing apparatus such as a video camera or a still camera.
2. Related Background Art
Various reflecting surfaces such as a mirror and a curved surface reflecting mirror have heretofore often been used in an optical system used in an image pickup apparatus such as a video camera or a still camera. Generally, a reflecting surface often comprises an optical polished surface sufficiently reduced in surface roughness and single-layer film of a metal or a dielectric material or multi-layer film comprising a combination thereof and evaporated on the optical polished surface.
If the refractive index and thickness of the film can be strictly controlled, there will be obtained an expected interference effect and a desired reflectance. Generally, a higher reflectance and a more desired spectral reflectance characteristic (spectrum) are obtained by the multi-layer film than by the single-layer film.
However, the multi-layer film is formed by alternately superposing substances relatively differing in refractive index upon one another with a uniform thickness and therefore, precise feeding of the control of various conditions for the evaporation is necessary. Therefore, the evaporating apparatus becomes large-scaled. Further, depending on the substances evaporated and the thickness and the number of layers, control and knowhow of the apparatus are necessary. Also, it is often the case that it is necessary to set conditions precisely, requiring much time, and this results in the high cost of a reflecting optical element.
On the other hand, there have heretofore been proposed various mirror optical systems using a reflecting mirror such as a concave mirror or a convex mirror instead of the lens of a photo-taking lens having a great full lens length to thereby bend the optical path efficiently and achieve the compactness of the optical system.
In the above-described prior-art reflecting optical element, there are many and complicated manufacturing processes for the formation of reflecting film for obtaining a desired reflectance, and this has resulted in a high cost which has posed a great problem during mass production.
Also, a mirror optical system using a plurality of reflecting mirrors has suffered from the problem that if the reflectance in each reflecting surface is low, the transmittance of the entire optical system becomes low and the effect of using the reflecting mirrors becomes reduced.
The present invention has as its object to solve the above-noted problems peculiar to the prior art and to provide an optical element of a novel construction which realizes desired optical action.
To solve the above object, the optical element of a first invention of the application is characterized by the provision of:
a base member formed of a material transmitting a light of a predetermined wavelength therethrough; and
an optical acting surface provided on the base member, the optical acting surface having a plurality of micro structures smaller than the predetermined wavelength for creating potential confining one of an electron and a dipole moment therein, and desired optical action utilizing the light of the predetermined wavelength discharged by the vibration of the electron or the dipole moment confined in the potential formed by the micro structures.
Also, the optical element of a second invention of the application is characterized by the provision of:
a base member formed of a material transmitting a light of a predetermined wavelength therethrough, the base member including:
two refracting surfaces; and
at least one reflecting surface having a plurality of micro structures smaller than the predetermined wavelength for creating potential confining one of an electron and a dipole moment therein, and reflecting the light of the predetermined wavelength by the utilization of the light of the predetermined wavelength discharged by the vibration of the electron or the dipole moment confined in the potential formed by the micro structures;
wherein the light of the predetermined wavelength incident from one of the two refracting surfaces is internally reflected by at least one reflecting surface, and thereafter is directed to the other refracting surface.
Further, the optical apparatus of a third invention of the application is characterized by the provision of the optical element of the first invention or the second invention of the application.